The present invention relates to ocular hypotensive agents which contains 13,14-dihydro-15-keto-prostaglandins.
Prostaglandins (hereinafter referred to as PGs) is the name given to the group of fatty acids which show various physiological activities and contained in human and animal tissues and organs. PGs essentially contain the prostanoic acid skeleton of the following formula: ##STR1## and some synthetic products may contain the above skeleton with some modification.
PGs are classified into several types according to their five-membered ring, for example, ##STR2## and the like. Further, they are classified into PG.sub.1 s containing 5,6-single bond: ##STR3## PG.sub.2 s containing 5,6-double bond: ##STR4## and PG.sub.3 s containing 5,6- and 17,18-double bonds: ##STR5##
PGs are known to have various pharmacological and physiological activities, for example, vasodilation, induction of inflammation, platelet aggregation, contraction of uterine muscle, enteron contraction and the like. However, PGs also possesses various other activities, therefore there are some problems to use them as medicines. That is, when PGs are administered to obtain a single pharmaceutical activity, they often exhibit other activities as side effects. Accordingly, the investigations of PGs as a medicine have aimed to enhance the emergency of the main pharmaceutical activity. However, these investigations have been insufficient.
Among PGs, for example, PGAs, PGDs, PGEs, PGFs are known to possess ocular hypotensive potency.
For example, there is described in Japanese Patent Application KOKAI No. 1418/1984 claiming a priority based on U.S. Ser. No. 374165(1982) by Laszlo Z. Bite that PGF.sub.2 has a high ocular hypotensive activity, and 15-keto-PGF.sub.2 .alpha. has also it though a very little; and further in Japanese Patent Application KOKAI No. 66122/1988 claiming priorities based on three U.S. Ser. Nos. 839056 (1986), 892387(1986) and 022046 (1987) that PGA, PGB and PGC can be used for a treatment of glaucoma.
However, when topical application of these PGs, topically to rabbit eyes, they are accompanied with transient ocular hypertensive response, and still pronounced conjunctival and iridal hyperemia, and further side effects such as lacrimation, eye mucus, lid closure and the like are observed. Accordingly, there are some problems when PGs are used as remedies for glaucoma or ocular hypotensive agents.
On the other hand, PGs wherein the carbon atoms at the 13-14 positions are saturated and the carbon atom at the 15 position forms a carbonyl group are found to exist in human or animal metabolites. These 13,14-dihydro-15-keto-prostaglandins (hereinafter referred to as 13,14-dihydro-15-keto-PGs) are known to be naturally produced metabolites by enzymatic metabolism of the corresponding PGs in vivo. These 13,14-dihydro-15-keto-PGs have been reported to hardly exhibit various physiological activities that PGs possess and be pharmacologically and physiologically inactive metabolites (see, Acta Physiologica Scandinavica, 66, p.509 (1966))